WASHINGTON (CNN) --The U.S. military will file charges against Army Capt. James Yee, the Islamic chaplain who has been held for nearly a month on suspicions of espionage and aiding the enemy, military officials told CNN Wednesday.

Yee was taken into custody after he was reported to have been found with classified material on his return to the United States from the U.S. naval base at Guantanamo Bay, Cuba, but was not charged with a crime.

Yee is a Chinese-American who converted to Islam after graduating from the U.S. Military Academy at West Point.

Military officials said "the expectation" is to file charges within the next few days, even if the initial charges are minor.

Charges of espionage, which Yee could eventually face, are likely to take considerable time to assemble.

By filing the less-severe charges first, the military will demonstrate that it is continuing to work on the case and that Yee is not languishing in the naval brig at Charleston, South Carolina, where he is being held, officials said.

Meanwhile, a military investigator has made his recommendations to court-martial authorities regarding more than 30 charges, including espionage, facing Senior Airman Ahmad al Halabi, according to his attorney, Maj. Jamie Key.

However, the investigator's recommendations have been classified. Key said it is unusual for the recommendations to be classified by the government.

The recommendations can be accepted or rejected by court-martial authorities, who have wide latitude on proceeding against al Halabi, regardless of the recommendations.

Al-Halabi was taken into custody July 23, but authorities did not announce his arrest until late September. He is being held at a prison facility at Vandenberg Air Force Base in California.

The investigation into the apparent infiltration of the remote Guantanamo Bay facility is ongoing, and a senior defense official has told CNN that more arrests may come.

Court documents obtained by CNN indicate that the offenses allegedly committed by al-Halabi at Guantanamo occurred between December 20, 2002, and July 23.

He is also charged with offenses at Travis Air Force base in California in September and November 2002, which allegedly occurred before he reported for duty at Camp Delta at Guantanamo.